MailFront

Protocol: smtp

The SMTP protocol module has the following features:

Handles RFC 2554 SMTP authentication. Note that the require-auth plugin and/or the relayclient plugin will need to be loaded to make use of this authentication.
Automatically handles either bare NL or RFC 821 / RFC 2821 compliant CR/NL end-of-line conventions.
Will drop connections on inactivity or too many errors.
All error responses are logged.
Handles (ignores) RFC 1869 extended parameters on the RCPT TO: and MAIL FROM: commands.
Configurable initial greeting.
Supports RFC 1870 SMTP Service Extension for Message Size Declaration.

Configuration

$MAXNOTIMPL: The maximum number of unimplemented commands (resulting in a "500 Not implemented." response) allowed in a session before dropping the connection. No default.
$SESSION_TIMEOUT: The number of seconds from the start of the session after which to drop the connection. Defaults to 86400 seconds (24 hours).
$SMTPGREETING: The greeting text to send on startup. If not set, the greeting is generated based on the domain name in ${$PROTO}LOCALHOST set by the invoking UCSPI server such as tcpserver.
$TIMEOUT: The number of seconds of inactivity after which to drop connections. Defaults to 1200 seconds (20 minutes).
$TLS_CERTFILE: The filename containing the TLS certificate and any intermediate certificates used to sign it. The file contents must be in PEM format. This setting is required for operation STARTTLS or SMTPS mode.
$TLS_COMPAT: Disable certain (security) features in TLS in order to maintain maximum compatibility with buggy clients.
$TLS_DH_PARAMS: The filename containing the Diffie-Hellman key exchange parameters, as generated by openssl dhparam or certtool --generate-dh-params. If not specified, default parameters are used.
$TLS_IMMEDIATE: If set, this plugin will switch to TLS mode on startup (if possible, see below). This is primarily useful for running mailfront as a SMTP submission server on TCP port 465 (SMTPS).
$TLS_KEYFILE: The filename containing the private key for to the certificate. The file contents must be in PEM format. If unset, it defaults to the value of $TLS_CERTFILE.
$TLS_PRIORITY: The GnuTLS priority string, which specifies the TLS session's handshake algorithms and options. See the manual page for more details on possible values. Defaults to "NORMAL", which represents all the known to be secure ciphersuites.